To compare the biomechanical performance of different implant-supported rehabilitation concepts in the atrophic maxilla by using finite element analysis.

Five three-dimensional finite element models were generated from CT data and classified as “All-on-4” (Model 1), “M-4” (Model 2), “V-4” (Model 3), zygomatic implants combined with conventional implants (Model 4), and “Quad-Zygoma” (Model 5). All materials were assumed linear elastic, homogeneous, and isotropic. Models were constrained at posterior and superior regions, and a unilateral vertical load of 150 N was applied to the right first molar via a 20 mm “foodstuff”. A mesh convergence analysis confirmed model reliability with an error below 3%. Stress distributions were evaluated by using von Mises, maximum principal (Pmax), and minimum principal (Pmin) stresses. All stresses were expressed in MPa (N/mm²).

The highest von Mises stresses were observed in Model 2, with values of 80.010 MPa in the implants, 62.961 MPa in the abutments, and 57.76 MPa in the metal framework. In contrast, the lowest stresses were recorded in Model 5, with corresponding values of 66.222 MPa, 61.564 MPa, and 42.209 MPa, respectively. Similarly, cortical bone exhibited the highest stress concentrations in Model 2 and the lowest in Model 5, with Pmax and Pmin values of 11.978 MPa and −49.535 MPa in Model 2, and 9.725 MPa and −22.206 MPa in Model 5, respectively. Notably, Pmin values in Models 4 and 5 were approximately 50% lower than those in Models 1–3. Trabecular bone stresses showed minimal variation across all models.

Although all models demonstrated acceptable biomechanical behavior, zygomatic implant configurations (Models 4 and 5) showed reduced stress concentrations, particularly in terms of compressive stresses in cortical bone. These findings may indicate a potential biomechanical advantage of zygomatic implant approaches, especially the “Quad-Zygoma” concept, in the rehabilitation of the atrophic maxilla.